使用cluster模块实现负载均衡，和多进程监听同一端口

node_cluster_http_server.js

import http from 'http';
import cluster from 'cluster';
import os from 'os';

const port = 3001;
// cpu核数
const numCpus = os.cpus().length;
console.log(`The num of cpu: ` + numCpus);

// 实现Load balancer
if (cluster.isMaster) {
  console.log(`[MASTER],PID:${process.pid}, STARTING...`);
  for (var i = 0; i < numCpus; i++) {
    cluster.fork();
  }
  cluster.on('listening', (worker, address) => {
    console.log(`listening... worker:${worker.id}, address:${address.port},
      worker pid: ${worker.process.pid}`);
  });

  cluster.on('fork', (...args) => {
    console.log(args);
  });

  cluster.on('exit', (worker, code, signal) => {
    console.log(`worker die... worker:${worker.id}, code:${code},
      signal: ${signal}`);
    // 注意：如果子进程worker抛出异常，则会触发该worker退出
    // 需要重新fork
    cluster.fork();
  });
} else {
  console.log(`[WORKER${cluster.worker.id}] STARTING...`);
  http.createServer((req, res) => {
    res.writeHead(200);
    res.end(`WorkerId:${cluster.worker.id},Pid:${cluster.worker.process.pid}`);
  }).listen(port || process.env.PORT);
}